Q.If \(u_i = \cfrac{x_i - 35}{10}\), \(∑f_i u_i = 30\), and \(∑f_i = 60\), then the value of \(\bar{x}\) is – (a) 40 (b) 20 (c) 80 (d) None of these
Answer: A
Here, \(a = 35\) and \(h = 10\).

∴ \(\bar{x} = a + \cfrac{\sum f_i u_i}{\sum f_i} × h\)
\(= 35 + \cfrac{30}{60} × 10 = 35 + 5 = 40\).
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